The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
In general, a high voltage battery and an inverter are applied to eco-friendly vehicles such as hybrid vehicles and electric vehicles, and a current sensor is used in an electric power system such as an inverter.
A controller of an eco-friendly vehicle constantly measures a current of a battery while driving and charging to control electric power and monitor states of the vehicle and various components.
A large current, as a direct current (DC) of up to 200 to 400 amperes (A), flows in an eco-friendly vehicle, and in order to measure the large current, a Hall effect current sensor is commonly used. A Hall effect sensor or a Hall sensor, which measures a magnetic field induced by a current to measure the current, is advantageously used as a non-contact type sensor, but has shortcomings in that a current value thereof under a condition of 0A used as a reference drifts.
Under the condition of 0A, a current of the current sensor drifts up to 3A according to changes in an ambient temperature, and in addition, there are variations in sensors. Thus, the controller should determine a current value (offset) corresponding to the condition of 0A before the current sensor is used.
In the related art, when a predetermined period of time has lapsed since the ignition was turned off, an offset current is measured under the condition of 0A. Here, offset currents are measured for a predetermined period of time tens to hundreds of times, and the measured offset currents are averaged.
The condition of 0A after the ignition is turned off is secured by turning off a battery or a main switch (relay) of a power source. That is, after the switch is turned off, 0A is checked and an offset current is subsequently measured. Thereafter, when the ignition is turned on, a current is calculated on the basis of the measured offset current.
In a case in which the offset current measured for a predetermined period of time is abnormal, the controller diagnoses failure, and when the ignition turned on next time, the controller continuously uses an immediately previous normal offset current.
However, in the related art, in a case in which an error occurs after the ignition is turned off or in a case in which the current sensor itself or power of the current sensor is abnormal when the ignition is turned on next time, an erroneous current value may be calculated and used.